You mention that you do not wish to communicate as you feel you should move on.
Given that this is the choice you have made, I think the best thing you can do for both yourself and the guy in question Is to send him one email making this point perfectly clear ,wishing him well and pointing out that you will not be replying ,unless of course your aim is to offer friendship. If you want to try the friendship route then you need to set limits as to how and when you contact each other.
Do however make sure you make your intentions as clear as a bell,to keep him dangling on a thread of false hopes would be cruel.
Also remember that you are not responsible for any future decisions he may make for himself.
It is not fair to either of you to remain in a relationship purely because you fear he may harm himself.
Make your mind up as quickly as possible and then stick with it.
Thats my opinion anyway,take it or leave it but remember he is responsible for him.